Guardrail System

ABSTRACT

A guardrail system including a sled designed to absorb the impact of a vehicle is disclosed. The sled forms part of the terminal portion of the guardrail system. The terminal portion of the guardrail system also includes one or more cables that are anchored to the ground and pass through the sled. The sled supports a cable break that is in engagement with the cable. The sled is supported by a releasable post that is released from its base upon the impact of a vehicle. The cable or cables extend for some distance from the sled along the guardrail system. Once the post supporting the sled is released from its base due to the impact of a vehicle, the sled can move along the cable with the friction between the cable brake and the cable gradually dissipating the energy from the impact.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to guardrail systems having impactabsorbing end units.

2. Description of the Prior Art

Guardrails are commonly provided along the sides of roadways to preventvehicles from going off the roadway in the event of the driver losingcontrol of the vehicle. In particular, where a precipice is locatedadjacent the roadway a guardrail can save the lives of a vehicle'soccupants by preventing the vehicle from going over the edge of theprecipice in the event of the driver losing control of the vehicle. Itis desirable for guardrail systems to also have impact absorbingproperties to minimize the risk of injury to the occupants of a vehiclethat impacts the guardrail system. Where one roadway intersects anotherroadway, for example, a break is created in the guardrail systemresulting in the creation of guardrail system terminal portions. Theimpact absorbing properties of the guardrail system are particularlyimportant at these end or terminal portions of the guardrail systembecause vehicles can potentially impact the terminus of the guardrailsystem head on resulting in far higher impact energies that are furtherconcentrated by a relatively small impact area at the terminus of theguardrail system. Consequently, the potential for catastrophic injuriesto a vehicle's occupants are far greater at the terminus of a guardrailsystem. For this reason guardrail systems having impact absorbingterminal portions have been proposed in the art. However, none are seento have the unique structure and advantages of the present invention aswill become apparent from the detailed description below.

SUMMARY OF THE INVENTION

The present invention is directed to a guardrail system having an impactabsorbing terminal portion and to novel components parts useful with aguardrail system.

The present invention includes a sled designed to receive the impact ofa vehicle. The sled forms part of the terminal portion of the guardrailsystem. The terminal portion of the guardrail system also includes oneor more cables that are anchored to the ground and pass through thesled. The sled supports a cable break that is in engagement with thecable. The sled is supported by a releasable post that is released fromits base upon the impact of a vehicle. The cable or cables extend forsome distance from the sled along the guardrail system. Once the postsupporting the sled is released from its base due to the impact of avehicle, the sled can move along the cable with the friction between thecable brake and the cable gradually dissipating the energy from theimpact. Thus the guardrail system greatly reduces the effect of theimpact on the vehicle and its occupants, which in turn reduces thelikelihood of serious injury to the occupants of the vehicle.

An advantage of the impact absorbing guardrail terminal portionaccording to the present invention over the prior art is that the cableof the present invention is routed along a non-tortuous path as itpasses through the cable brake. The known prior art maintains the cablein a tortuous configuration such that upon impact the cable is subjectedto severe bends or changes in direction that can excessively strain thecable, which can lead to breakage and fraying of the cable.

The invention also encompasses several novel and unique components thatcould have utility in various other contexts in addition to theguardrail system of the present invention. These unique componentsinclude a cable brake system, a releasable guardrail post, and afrangible guardrail post.

Accordingly, it is an object of the present invention to provide aterminal portion for a guardrail system that has impact absorbingproperties.

Another object of the present invention is to provide animpact-absorbing guardrail terminal portion that includes a cable and acable brake means, in which the cable follows a non-tortuous paththrough the cable brake means.

Another object of the present invention is to provide a guardrail systemthat incorporates an impact absorbing terminal portion.

A further object of the present invention is to provide a cable brakesystem.

Yet another object of the present invention is to provide a releasableguardrail post.

Yet another object of the present invention is to provide a yieldableguardrail post.

These and other objects of the present invention will become apparentfrom the detailed description below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view in side elevation of a guardrail system according tothe present invention.

FIG. 2 is a top plan view of a guardrail system according to the presentinvention.

FIG. 3 is an isometric view from the left of a guardrail systemaccording to the present invention.

FIG. 4 is an isometric view from the right of a guardrail systemaccording to the present invention.

FIG. 5 is a fragmentary view showing the sled and ground anchorstructure of a guardrail system according to the present invention.

FIG. 6 is a fragmentary view showing the cable guide of a guardrailsystem according to the present invention.

FIG. 7 is a fragmentary view showing a mounting bracket of a guardrailsystem according to the present invention having means for anchoring theends of the cables of the guardrail system.

FIG. 8 is a view in side elevation of the sled of a guardrail systemaccording to the present invention.

FIG. 9 is an isometric view of the sled of a guardrail system accordingto the present invention.

FIG. 10 is an isometric view of the sled of a guardrail system accordingto the present invention with the protective cover removed.

FIG. 11 is a cross section of a view in side elevation of the sled of aguardrail system according to the present invention with the catchmember in the lowered position.

FIG. 12 is a cross section of a view in side elevation of the sled of aguardrail system according to the present invention with the catchmember in the raised position.

FIG. 13 is a top plan view of the sled of a guardrail system accordingto the present invention.

FIG. 14 is a top plan view of the sled of a guardrail system accordingto the present invention with the protective cover removed and the cablebrake pads positioned near the cable inlet of the upper cable brakehousing.

FIG. 15 is a top plan view of the sled of a guardrail system accordingto the present invention with the protective cover removed and the cablebrake pads positioned near the cable outlet of the upper cable brakehousing.

FIG. 16 is a top plan view of the upper cable brake housing of aguardrail system according to the present invention the tapering sidesof the cable brake housing.

FIG. 17 is a top plan view of an assembly including the brake pads,collar, and wedges of a cable brake of a guardrail system according tothe present invention.

FIG. 18 is an isometric view of an assembly including the brake pads,collar, and wedges of a cable brake of a guardrail system according tothe present invention.

FIG. 19 is an exploded view of an assembly including the brake pads,collar, and wedges of a cable brake of a guardrail system according tothe present invention.

FIG. 20 is an exploded view of an assembly including the brake pads,collar, and wedges of a cable brake of a guardrail system according tothe present invention shown in relation to one of the cables of aguardrail system.

FIG. 21 is an isometric view of a brake pad of a cable brake of aguardrail system according to the present invention.

FIG. 22 is a top plan view of the ground anchor structure of a guardrailsystem according to the present invention.

FIG. 23 is a cross section of a view in side elevation of the groundanchor structure of a guardrail system according to the presentinvention.

FIG. 24 is an isometric view of the ground anchor structure of aguardrail system according to the present invention.

FIG. 25 is another isometric view of the ground anchor structure of aguardrail system according to the present invention.

FIG. 26 is a fragmentary isometric view of the ground anchor structureof a guardrail system according to the present invention showing theangled plates of the ground anchor structure in greater detail.

FIG. 27 is an isometric view of the cable guide of a guardrail systemaccording to the present invention.

FIG. 28 is an isometric view of the mounting bracket of a guardrailsystem according to the present invention with means for anchoring theends of the cables of the guardrail system.

FIG. 29 is an exploded view showing the mounting bracket of a guardrailsystem according to the present invention having means for anchoring theends of the cables of the guardrail system and shown in relation to theends of the cables.

FIG. 30 is an isometric view of a yieldable guardrail post of aguardrail system according to the present invention.

FIG. 31 is a view in side elevation of a yieldable guardrail post of aguardrail system according to the present invention.

FIG. 32 is a head-on view of a yieldable guardrail post of a guardrailsystem according to the present invention.

FIG. 33 is a view in side elevation of a second embodiment of theguardrail system according to the present invention.

FIG. 34 is a top plan view of a second embodiment of the guardrailsystem according to the present invention.

FIG. 35 is an isometric view from the left of a second embodiment of theguardrail system according to the present invention.

FIG. 36 is an isometric view from the right of a second embodiment ofthe guardrail system according to the present invention.

FIG. 37 is a view in side elevation of a releasable guardrail postaccording to the present invention.

FIG. 38 is an isometric view of a releasable guardrail post according tothe present invention.

FIG. 39 is a top plan view of a releasable guardrail post according tothe present invention.

FIG. 40 is a view in side elevation of the catch member and lever arm ofa releasable guardrail post according to the present invention.

FIG. 41 is an isometric view of the catch member and lever arm of areleasable guardrail post according to the present invention.

FIG. 42 is a head-on view of the catch member and lever arm of areleasable guardrail post according to the present invention.

FIG. 43 is a view in side elevation of the catch member of a releasableguardrail post according to the present invention.

FIG. 44 is a view in side elevation from the left of the beam of thereleasable guardrail post according to the present invention.

FIG. 45 is an isometric view of the beam of a releasable guardrail postaccording to the present invention.

FIG. 46 is a top plan view of the beam of a releasable guardrail postaccording to the present invention.

FIG. 47 is a head-on view of the beam of a releasable guardrail postaccording to the present invention.

FIG. 48 is an isometric view of the base plate of a releasable guardrailpost according to the present invention.

FIG. 49 is a view in side elevation of the base plate of a releasableguardrail post according to the present invention.

FIG. 50 is a head-on view of the base plate of a releasable guardrailpost according to the present invention.

FIG. 51 is a top plan view of the base plate of a releasable guardrailpost according to the present invention.

FIG. 52 is a view in side elevation from the right of the beam of thereleasable guardrail post according to the present invention.

FIG. 53 is a view in side elevation from the right of the sled of aguardrail system according to the present invention.

FIG. 54 is a view in side elevation from the left of the sled of aguardrail system according to the present invention.

FIG. 55 is a view in side elevation from the right of the catch memberand lever arm of a guardrail system according to the present invention.

FIG. 56 is a view in side elevation from the left of the catch memberand lever arm of a guardrail system according to the present invention.

FIG. 57 is a view from the vantage point of oncoming traffic showing thebeam of a guardrail system according to the present invention with analternative type of guide.

Similar reference characters denote corresponding features consistentlythroughout the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1-32 and 53-57, the present invention is directed toa guardrail system 100 having an impact absorbing terminal portion. Theinvention also includes a yieldable post design and a releasable postdesign that may be used as part of the guardrail system or separately.The guardrail system 100 comprises a sled 102, one or more guardrailposts 104, 106, one or more cables 108, 110, and one or more cablebrakes 112, 114 corresponding in number to the cables 108, 110. Theillustrated guardrail posts 104, 106 are each adapted for being fixed tothe ground by having an elongated portion that can be buried at least inpart in or below the ground to thereby fix or anchor the guardrail postto the ground.

In the illustrated example, the guardrail system 100 is provided withtwo cables 108 and 110. The cables 108, 110 are preferably steel cablesthat are made from multiple strands of steel wire that are woven,twisted or braided together to form a steel cable. Each of the cables108, 110 has a portion extending between the sled 102 and the guardrailpost 104 closest to the sled 102. Each of the cables 108, 110 also has aportion extending between the sled 102 and a respective ground anchorlocation 116, 118. In use the sled 102 is positioned between theguardrail post 104 that is closest to the sled and the ground anchorlocations 116, 118.

The cable brakes 112 and 114 are supported by the sled 102. The cablebrakes 112 and 114 are structurally identical to one another. Each ofthe cable brakes 112 and 114 comprise at least a first brake pad 120 anda second brake pad 122 positioned on opposite sides of a respective oneof the cables 108, 110. The first brake pad 120 and the second brake pad122 of each of the cable brakes 112 and 114 frictionally engage arespective one of the cables 108, 110 in use.

When the guardrail system is installed on a side of a road, the sled 102can move along the cables 108, 110 upon impact of a vehicle (not shown)on the sled 102. The vehicle would impact the sled 102 with kineticenergy that must be dissipated gradually in order to bring the vehicleto a stop in a manner that reduces the likelihood and severity ofinjuries to the occupants of the vehicle. The frictional forces betweenthe cables 108, 110 and the first and second brake pads 120, 122 of thecable brakes 112, 114, respectively, dissipate at least a portion of thekinetic energy of the vehicle on impact as the sled 102 moves along thecables 108, 110 from its initial position toward the guardrail post 104nearest the sled 102. By selecting a sufficiently large predeterminedvalue for the frictional forces between the cables 108, 110 and thefirst and second brake pads 120, 122 of the cable brakes 112, 114,respectively, and selecting a sufficiently long distance between thesled 102 and the guardrail post 104 nearest the sled 102, a verysubstantial portion of the kinetic energy of the vehicle on impact canbe dissipated by the frictional engagement between the cables 108, 110and the brake pads 120, 122.

Each of the cable brakes 112, 114 includes a cable brake housing 124,126, respectively, that is incorporated in the sled 102. The first brakepad 120 and the second brake pad 122 for each of the cable brakes 112,114 are received in the respective cable brake housing 124, 126.

Each of the cable brake housings 124, 126 has a cable inlet 128, a cableoutlet 130, and opposing sidewall portions 132 and 134 that are taperingfrom the cable inlet 128 to the cable outlet 130 such that the opposingsidewall portions 132, 134 are closer together near the cable outlet 130as compared to the opposing sidewall portions 132, 134 near the cableinlet 128. The tapering sidewall portions 132, 134 of each cable brakehousing 124, 126 engage the first and second brake pads 120, 122 of therespective cable brake 112, 114 as the sled 102 moves along the cables108, 110 upon impact of a vehicle on the sled 102. Furthermore, theengagement of the tapering sidewall portions 132, 134 of each cablebrake housing 124, 126 with the first and second brake pads 120, 122 ofthe respective cable brake 112, 114 moves the first and second brakepads 120, 122 of the cable brakes 112, 114 with the sled 102 along thecables 108, 110 as the sled 102 moves along the cables 108, 110 uponimpact of a vehicle on the sled 102.

As the sled 102 moves along the cables 108, 110 due to the impact of avehicle on the sled 102, the tapering opposing sidewall portions 132,134 of each cable brake housing 124, 126 tend to more forcefully squeezethe respective first and second brake pads 120, 122 toward one anothersuch that the frictional forces between the respective cable 108, 110and the respective first and second brake pads 120, 122 are increased.

The first brake pad 120 of each cable brake 112, 114 has a threaded hole136 provided at a location that is at spaced separation from a surfaceportion 138 of the first brake pad that is in contact with therespective cable 108, 110 when the cable brake is in use. Similarly, thesecond brake pad 122 of each cable brake 112, 114 has a threaded hole140 provided at a location that is at spaced separation from a surfaceportion 142 of the second brake pad 122 that is in contact with therespective cable 108, 110 when the cable brake is in use. The surfaceportions 138 and 142 are in the form of tapering channels that arenarrower at their end closest to the cable outlet of the respectivebrake housing 124, 126 as compared to their end that is farthest fromthe cable outlet of the respective brake housing 124, 126. The surfaceportions 138 and 142 have cross sections that are in the form ofcircular arcs.

Each of the cable brakes 112, 114 further includes a collar 144, a pairof wedges 146, 148, and a pair of bolts 150, 152. The collar 144 has afirst surface 154 that faces away from the first and second brake pads120, 122 when the respective cable brake 112 or 114 is fully assembled.The first surface 154 of the collar 144 is inclined from the centerline156 toward either side 158, 160 of the first surface 154, such that thecenterline 156 of the first surface 154 of the collar 144 is depressedrelative to both of the sides 158, 160 of the first surface 154 of thecollar 144. Therefore, the first surface 154 of the collar 144 slopesforward toward the nearest guardrail post 104 on either side of thecenterline 156. The collar 144 also has an elongated slot 162 extendingon either side of the centerline 156. The slot 162 has a widened middleportion 164 through which the respective cable 108 or 110 passes whenthe cable brakes 112, 114 are in operation. The widened middle portion164 has an outline that follows a circular arc on either side of theslot 162. The widened middle portion 164 has a diameter that is largeenough to allow the cable 108 or 110 to pass through the middle portionof the slot 162.

Each of the pair of bolts 150, 152 has a head 166 and a shaft 168 thatis threaded at least in part. Each of the pair of wedges 146, 148 has ahole 170, 172, respectively, that is sized to provide clearance for theshaft 168 of a respective one of the pair of bolts 150, 152. The slot162 is sized to provide clearance for the shaft 168 of each of the pairof bolts 150, 152 and a respective one of the cables 108, 110, such thatthe shaft 168 of each of the pair of bolts 150, 152 can pass through thehole 170, 172 of a respective one of the pair of wedges 146, 148 and theslot 162 to engage a respective one of the threaded holes 136, 140 ofthe first and second brake pads 120, 122. In the illustrated embodiment,the slot 162 is sized to be wide enough on either side of the middleportion 164 to provide clearance for the shaft 168 of a respective oneof the pair of bolts 150, 152.

To assemble one of the cable brakes 112, 114 each of the pair of wedges146, 148 is positioned in contact with a respective sloping portion ofthe first surface 154 of the collar 144 on either side of the centerline156 of the first surface 154 of the collar. Then each of the pair ofbolts 150, 152 is positioned such that its shaft 168 passes through thehole 170, 172 of the respective one of the pair of wedges 146, 148 andthe slot 162 and engages a respective one of the threaded hole 136 ofthe first brake pad 120 and the threaded hole 140 of the second brakepad 122. Tightening the pair of bolts 150, 152 with the head 166 of eachof the bolts 150, 152 being in contact with the respective one of thepair of wedges 146, 148 tends to force the first and second brake pads120, 122 toward one another such that frictional forces between thecable 108 or 110 and the first and second brake pads 120, 122 of therespective cable brake are increased.

Each of the cables 108, 110 has a longitudinal axis 182, 184,respectively. Each of the pair of wedges 146, 148 of each cable brake112, 114 has a thick side 174 and a thin side 176. The thin side 176 isthinner or narrower than the thick side 174 and can be so narrow as toform a sharp edge. The pair of wedges 146, 148 are positioned onopposite sides of the centerline 156 of the first surface 154 of thecollar 144 with a respective one of the cables 108, 110 passing betweenthe pair of wedges 146, 148. Each of the pair of wedges 146, 148 isplaced in contact with the respective sloping portion of the firstsurface 154 of the collar 144 with its thick side 174 being positionedcloser to the centerline 156 of the first surface 154 of the collarcompared to its thin side 176, such that in operation the head 166 ofeach of the pair of bolts 150, 152 is in contact with a front surface178, 180 of a respective one of the pair of wedges 146, 148 that isessentially perpendicular to the longitudinal axis 182, 184 of therespective cable 108, 110.

As an alternative to the illustrated example, the cable brakes could beassembled with the surface 154 facing the first and second brake pads120, 122, if the brake pads 120, 122 are provided with beveled surfacesthat match the slope of the inclined surfaces on either side of thecenterline of the surface 154 of the collar 144. Thus, the bolts 150,152 can extend through the collar 144 and engage the threaded holes inthe brake pads 120, 122 directly in order to provide the requiredclamping action upon tightening of the bolts. As yet anotheralternative, the collar 144 could be provided surfaces on both sidesthat are bilaterally inclined in relation to the centerline of thesurface like the surface 154. In this case brake pads having the beveledsurfaces would be positioned on one side of the collar and the wedges146, 148 would be positioned on the other side of the collar. The bolts150, 152 can then extend through the wedges 146, 148 and the collar 144and engage the threaded holes in the brake pads in order to provide therequired clamping action upon tightening of the bolts.

The guardrail system 100 further includes a base 186 adapted for beinganchored or fixed to the ground. The base 186 includes a base plate 188and an elongated base post 190. The base post 190 is adapted for beingburied at least in part in the ground to thereby anchor the base 186 tothe ground in the illustrated embodiment. The base post 190 has a topthat remains above ground. The base plate 188 can be attached to the topof the base post 190 by, for example, welding. In the illustratedexample, the base plate 188 has a sleeve 187 welded to its bottomsurface. The sleeve 187 fits into the top of the base post 190, and thesleeve 187 and the base post 190 each have one or more holes such thatthe holes of the sleeve 187 register with the holes of the base post 190to allow pins, rivets, bolts or the like to be used to attach the baseplate 188 to the base post 190.

The sled 102 further includes at least one skid plate 192 capable ofbeing supported on top of the base plate 188 for essentially rectilinearmovement parallel to the base plate 188 upon the impact of a vehicle onthe sled 102. Once the guardrail system 100 is installed at a site, thecables 108, 110 will be in tension. In the illustrated embodiment, thebase plate 188 is inclined such that it slopes upward or rises in thedirection of oncoming traffic shown by arrow T.

The base plate 188 is provided with a guide 194 that assists in guidingthe skid plate 192, and thus the sled 102, during the initialrectilinear movement of the skid plate 192 and sled 102 relative to thebase plate 188 due to the impact of a vehicle. The guide 194 can take avariety of forms as shown in the drawings. The guide 194 can be in theform of a channel 196 that receives a portion of the skid plate 192 oncethe guardrail system 100 is installed at a given site. The channel 196is provided on one side of the base plate 188 and is coextensive withthe side of the base plate 188 that is substantially perpendicular tothe cables 108, 110 and is upstream of the other sides of the base plate188 in relation to the direction of flow of traffic. In other words, thechannel 196 is coextensive with the side of the base plate 188 that isclosest to the ground anchor locations 116, 118 after installation. Theends of the channel 196 can be closed off as shown in the drawings toform a pocket 196. The channel or pocket 196 receives the portion of theskid plate 192 that includes the side or edge of the skid plate 192 thatis closest to the ground anchor locations 116, 118 after installation.The pocket 196 and the sloping base plate 188 can cooperate to keep thesled 102 in position over the base 186 during assembly and thus canfacilitate the installation of the guardrail system 100.

In another one of the illustrated embodiments, the guide 194 is in theform of a channel 198 that receives a portion of the skid plate 192 oncethe guardrail system 100 is installed at a given site. In this instance,the guide 194 is in the form of two opposing channels 198 provided oneither side of the base plate 188 that receive portions of the skidplate 192 on either side of the skid plate 192. The opposing channels198 are provided on either side of the base plate 188 such that theyextend substantially parallel to the cables 108, 110.

The sled 102 further includes a beam 200. The beam 200 supports thecable brake housings 124, 126 and the skid plate 192 is attached to thebeam 200 at the lower end of the beam 200. The guardrail system 100further includes a catch member 202 that is pivotally attached to thebeam 200. The catch member 202 pivots about a horizontal pivot axis andthe catch member 202 is pivotally movable between a raised position anda lowered position.

The sled 102 is mounted on the base 186 with the catch member 202positioned substantially on the side of the beam 200 that faces towardoncoming traffic. When the catch member 202 is in the lowered position,the catch member 202 has a portion 204 that overlaps at least a portionof the base 186, such as the base plate 188, as seen from the view ofoncoming traffic such that movement of the sled 102 relative to the base186 in the same direction as oncoming traffic would essentially beprevented by interference between the catch member 202 and the base 186.

The guardrail system 100 further includes a lever arm 206 that isattached to the catch member 202 such that lever arm 206 and the catchmember 202 move as a unit. The catch member 202 is movable between thelowered position and the raised position responsive to the lever arm 206moving between a first position and a second position. The catch member202 is in the lowered position when the lever arm 206 is in the firstposition. The catch member 202 moves toward the raised position as thelever arm 206 is moved toward the second position which is closer to thebeam 200 compared to the first position.

After installation of the guardrail system 100 at a site, the sled 102is mounted on the base 186 with the catch member 202 positionedsubstantially on the side of the beam 200 that faces toward oncomingtraffic. The catch member 202 is normally in the lowered position andthe cables 108, 110 are in engagement with the cable brakes 112, 114.When vehicle is about to collide with the sled 102, the vehicle firstimpacts the lever arm 206 and moves it to the second position before thevehicle impacts the sled 102. Therefore, the catch member 202 is movedto the raised position before the vehicle impacts the sled 102.Accordingly, the sled 102 is first freed for rectilinear motion relativeto the base 186 before the vehicle impacts the sled 102, such that thesled 102 can move relative to the base due to impact energy beingimparted to the sled 102 by the vehicle and thus gradually slow down thevehicle.

The catch member 202 includes two parallel plates 208, 210 that arespaced apart from one another and a catch plate 212 that extends betweenthe parallel plates 208, 210. Each of the parallel plates 208, 210 isprovided with a hole 214 and 216, respectively. The hole 214 of thefirst one of the parallel plates 208 is in registry with the hole 216 ofthe second one of the parallel plates 210. Each hole 214, 216 in eachparallel plate 208, 210 is located at spaced separation from the catchplate 212. One or more shafts or pins 218 pass through one or moreopenings, there are two openings 220, 221 in the illustrated example, inthe beam 200 and through each hole 214, 216 in each parallel plate 208,210 to thereby pivotally attach the catch member 202 to the beam 200. Animpact plate 222 is preferably attached to the lever arm 206 to providea larger surface area over which the impact of a vehicle can operate thelever arm 206 and consequently the catch member 202.

The guardrail system 100 may also include one or more guardrail sections224. The guardrail sections 224 are preferably of the type having aW-shaped cross section. Each guardrail section has a front side 226 anda back side 228. The front side 226 has a central valley or trough 230that extends longitudinally along the length of the guardrail section224 and the front side 226 also has a pair of peaks 232, 234 on eitherside of the valley that also extend along the length of the guardrailsection. The back side 228 has a central peak 236 that extendslongitudinally along the length of the guardrail section 224 and theback side 228 also has a pair of valleys 238, 240 on either side of thepeak 236 that also extend along the length of the guardrail section 224.

Each of the cables 108, 110 has a first end and a second end. The firstend of each cable 108, 110 is anchored to the ground at the respectiveground anchor location 116, 118 and the second end of each cable 108,110 is anchored in place at a location 242, 244, respectively, over theback side 228 of the guardrail section 224 when the guardrail system isinstalled on the side of a road.

In the illustrated embodiment, the guardrail system 100 includes aplurality of guardrail sections 224. At least one of the guardrailsections 224 is supported at least in part by the guardrail post 104nearest to the sled 102. The second end of each cable 108, 110, near thelocations 242, 244, respectively, is anchored in position in therespective trough 238, 240 of one of the plurality of guardrail sections224 when the guardrail system 100 is installed on the side of a road.

The second end of each cable 108, 110, near the locations 242, 244,respectively, is provided with a threaded shaft 246, 248, respectively,that is essentially coaxial with the respective cable 108, 110. Theguardrail system 100 further includes a mounting bracket 250. Themounting bracket 250 is used for attaching at least one of the pluralityof guardrail sections 224 to one of the guardrail posts 104, 106. Inparticular, the mounting bracket 250 is used for attaching at least oneof the guardrail sections 224 to one of the guardrail posts 104, 106corresponding to the locations 242, 244 where the second ends of thecables 108, 110 are anchored. The mounting bracket 250 includes at leastone sleeve having a bore with a diameter that is large enough to allowone of the threaded shafts 246, 248 to extend through the bore of thesleeve. In the illustrated embodiment, the mounting bracket 250 includestwo sleeves 252, 254, corresponding to the two cables 108, 110. Eachsleeve 252, 254 has a bore 256, 258, respectively, with a diameter thatis large enough to allow a respective one of the threaded shafts 246,248 to extend through the bore of the sleeve 252, 254.

One threaded nut 260, 262 capable of engaging the threaded shaft 246,248, respectively, is provided for each threaded shaft 246, 248. Eachnut 260, 262 is too large to pass through the bore 256, 258 of therespective sleeve 252, 254. Each nut 260, 262 engages the respectivethreaded shaft 246, 248 with the cables 108, 110 extending toward thesled 102, on an opposite side of the sleeves 252, 254 relative to thenuts, to thereby anchor the second end of each of the cables 108, 110 inposition over the back side of one of the guardrail sections 224, whenthe guardrail system 100 is installed on the side of a road.

The mounting bracket 250 has a bottom plate 251 and two side plates 253,255 on either side of the bottom plate 251. The two side plates 253, 255are at angles of greater than 90° with respect to the bottom plate 251to give the mounting bracket 250 an approximately V-shaped crosssection. The mounting bracket 250 is dimensioned and configured to fitover the middle peak 236 of the back side 228 of the guardrail sections224. The bottom plate 251 has holes that allow it to be bolted to theguardrail posts 104, 106. The side plates 253, 255 have holes that allowthe guardrail sections 224 to be bolted to the mounting bracket 250.Standard or frangible bolts may be used as necessary, both to bolt theguardrail sections 224 to the mounting bracket 250 and to bolt themounting bracket 250 to the guardrail posts 104, 106, depending upon thelocation of the mounting bracket 250 in the guardrail system 100 as willbe described later. The mounting bracket 250 also has flanges 257, 259provided at the edges of the side plates 253, 255 that are distal fromthe bottom plate 251. The flanges 257, 259 are positioned approximatelyin the valleys 238, 240 on either side of the middle peak of the backside 228 of the guardrail sections 224 when a guardrail section 224 isbolted to the mounting bracket 250. Each of the sleeves 252, 254 isattached, for example by welding, to the mounting bracket 250 at theangle formed between a respective one of the flanges 257, 259 and arespective one of the side plates 253, 255.

The guardrail system 100 also includes an anchor structure 264 foranchoring the first end of each of the cables 108, 110 to the ground atthe ground anchor locations 116, 118, respectively, when the guardrailsystem 100 is installed on the side of a road. The anchor structure 264includes an anchor post 266, a pair of bars 268 and 270, and at leastone angled plate. In the illustrated embodiment, there are two angledplates 272 and 274, one provided for each of the cables 108, 110. Theanchor post 266 is adapted for being buried at least in part belowground to thereby anchor the anchor post 266 to the ground. In use theanchor post 266 is positioned upstream of the base post 190 relative tothe direction of traffic flow in a lane of the road nearest theguardrail system 100 as indicated by the arrow T.

The bars 268, 270 extend in parallel between the anchor post 266 and thebase post 190. Each of the pair of bars 268, 270 has a longitudinalaxis, a first end, and a second end. Each of the pair of bars 268, 270is attached to the anchor post 266 proximate its first end, and each ofthe pair of bars 268, 270 is attached to the base post 190 proximate itssecond end. The pair of bars 268, 270 can be attached to the anchor post266 and the base post 190 using means that include but are not limitedto bolts, rivets, and welding. In the illustrated example, the pair ofbars 268, 270 are attached to a cap 267 that fits over the top of theanchor post 266. The cap 267 has three sides and the pair of bars 268,270 are welded to the cap 267 on either side to for a five sided boxthat fits over the top of the anchor post 266. The pair of bars 268, 270and the top of the anchor post 266 have holes that register with oneanother, and one or more bolts or rivets can be used to attach the pairof bars 268, 270, the cap 267, and the anchor post 266 together.Alternatively, the cap 267 can be five sided and also have holes thatregister with the holes in the pair of bars 268, 270 and the top of theanchor post 266. Again, one or more bolts or rivets can be used toattach the pair of bars 268, 270, the cap 267, and the anchor post 266together. The angled plates 272, 274 extend like rungs in a ladderbetween the pair of bars 268, 270 at positions intermediate the anchorpost 266 and the base post 190. The angled plates 272, 274 are spacedapart from one another. Each of the angled plates 272, 274 has aninclined portion 276, 278, respectively, that is angled relative to thelongitudinal axis of each of the pair of bars 268, 270 such that in usethe inclined portion rises upward relative to the ground with decreasinghorizontal distance from the anchor post 266. The inclined portions 276,278 can be attached to the pair of bars 268, 270 using means thatinclude but are not limited to bolts, rivets, and welding. Each of thecables 108, 110, is provided with a threaded shaft 280, 282,respectively, at its first end. Each of the inclined portions 276, 278has an opening 284, 286, respectively, that is large enough to allow therespective threaded shafts 280, 282 to extend through the openings 284,286 of the inclined portions 276, 278.

A pair of threaded nuts 288 and 290 capable of engaging the threadedshafts 280, 282, respectively, are provided for anchoring the first endsof the cables 108, 110 at the ground anchor locations 116, 118. Thethreaded nuts 288, 290 are too large to pass through the respectiveopenings 284, 286 of the inclined portions 276, 278. Each of the nuts288, 290 engages a respective one of the threaded shafts 280, 282 at thefirst ends of the cables 108, 110 with the cables 108, 110 extendingbetween the inclined portions 276, 278 and the sled 102 on the sides ofthe inclined portions 276, 278 opposite the sides on which the nuts 288,290 are located to thereby anchor the first ends of the cables 108, 110in position at the ground anchor locations 116, 118 once the guardrailsystem 100 is installed on the side of a roadway. In the illustratedembodiment, the openings 284, 286 in the inclined portions 276, 278 arein the form of U-shaped slots to provide for greater ease of assembly ofthe guardrail system 100.

The manner in which the base post 190 or any of the guardrail posts 104,106, or the anchor post 266 are fixed to the ground can vary dependingupon the requirements of the particular location where the guardrailsystem 100 is being installed, especially the nature of the surface overwhich the guardrail system 100 is to be installed. For example, if theguardrail system 100 is being installed over a concrete foundation, theelongated portions of the base post 190, the guardrail posts 104, 106,and the anchor post 266 that are intended for being buried under theground surface can be replaced by a flange or plate having a pluralityof holes attached to the bottom of these various posts. Each of thesevarious posts can then be positioned on the concrete foundation suchthat anchor bolts embedded in the concrete foundation extend through theholes in the flange or plate attached to the bottom of the post.Threaded nuts engaging the anchor bolts can then be tightened down overthe flange or plate attached to the bottom of the post in order tosecure or fix the post in place over the concrete foundation. As yetanother alternative, the elongated portions of the base post 190, theguardrail posts 104, 106, and the anchor post 266 that are intended forbeing buried under the ground surface can be placed in holes in theground that are backfilled with concrete. Furthermore, one or more ofthe various modes for securing or fixing the various posts in place thatare mentioned above can be combined as conditions require in a giveninstallation of the guardrail system 100.

As a way of conveniently referencing parts of the invention, the cable108, the cable 110, the cable brake 112, the cable brake 114, the sleeve252, the sleeve 254, the angled plate 272, the angled plate 274, thethreaded shaft 246, the threaded shaft 280, the threaded shaft 248, thethreaded shaft 282, the nut 260, the nut 288, the nut 262, the nut 290,the ground anchor location 116, the location 242, the ground anchorlocation 118, the location 244, the brake pad 120 of the cable brake112, the brake pad 122 of the cable brake 112, the brake pad 120 of thecable brake 114, and the brake pad 122 of the cable brake 114 arerespectively referred to as the first cable, the second cable, the firstcable brake, the second cable brake, the first sleeve, the secondsleeve, the first angled plate, the second angled plate, the firstthreaded shaft, the second threaded shaft, the third threaded shaft, thefourth threaded shaft, the first threaded nut, the second threaded nut,the third threaded nut, the fourth threaded nut, the first anchorlocation, the second anchor location, the third anchor location, thefourth anchor location, the first brake pad, the second brake pad, thethird brake pad, and the fourth brake pad in some of the appendedclaims.

In the illustrated embodiments of the guardrail system, one or more ofthe guardrail posts nearest the sled 102 are yieldable guardrail post104 designed to yield at a predetermined impact force. The guardrailposts 106 are standard guardrail posts. The use of yieldable guardrailpost 104 for the several guardrail posts nearest the sled 102 providesan added measure of safety in the event that the energy from the impactof the vehicle is not completely dissipated before the sled 102 reachesthe nearest guardrail post 104 by providing for continued gradualdissipation of the impact energy. Thus vehicles with a wider rangeweights and speeds can more safely be brought to a stop in head-oncollisions with the end unit or portion of the guardrail system 100.

Each yieldable guardrail post 104 includes a first elongated member 292,a second elongated member 294, and a reinforcement plate 296. The firstelongated member 292 has an elongated back plate 298 and two side plates300, 302 that are parallel to one another. The side plates 300, 302project at right angles to the back plate 298 on either side of the backplate 298 to thereby give the first elongated member 292 achannel-shaped cross section. The second elongated member 294 has anelongated back plate 304 and two side plates 306, 308 that are parallelto one another. The side plates 306, 308 of the second elongated member294 project at right angles to the back plate 304 of the secondelongated member 294 on either side of the back plate 304 of the secondelongated member 294 to thereby give the second elongated member 294 achannel-shaped cross section The first elongated member 292 and thesecond elongated member 294 are attached together with their respectiveback plates 298, 304 in abutting contact so as to form a beam 310 havingan H-shaped cross section. The second elongated member 294 has a slit312 transverse to the longitudinal axis of the second elongated member294 that transects the second elongated member. When the post 104 isinstalled, the side with the slit 312 faces toward oncoming traffic.

The reinforcement plate 296 is attached to the back plate 298, 304 ofone of the elongated members 292, 294 proximate the slit 312 in thesecond elongated member 294. In the illustrated embodiment, thereinforcement plate 296 is attached to the back plate 304 of one of thesecond elongated member 294 and faces toward oncoming traffic when thebeam 104 is installed. In the illustrated embodiment, two rows of rivets314, 316 distributed along the length of the beam 310 and passingthrough back plates 298, 304 are used to attach the first elongatedmember 292 and the second elongated member 294 together. There is a gapin the rows of rivets 314, 316 corresponding to the location of thereinforcement plate 296 along the beam 310. The reinforcement plate 296is attached to the back plate 304 of the second elongated member 294 bytwo rows of rivets 318, 320. The two rows of rivets 318, 320 aredistributed along the length of the reinforcement plate 296 and passthrough back plate 304. The two rows of rivets 318, 320 are spaced moreclosely together compared to the rows of rivets 314, 316. The gauge,i.e. thickness, of the steel used and the dimensions of the firstelongated member 292, the second elongated member 294, and thereinforcement plate 296 can be varied to determine the predeterminedthreshold impact energy at which the post 104 will yield. A specificpredetermined threshold impact energy at which the post 104 will yieldcan be determined for a specific application by routine experimentation.

In the illustrated embodiment, each of the guardrail sections 224overlaps a portion of each adjacent guardrail section 224 over at leastone guardrail post 104, 106 that is a common support for both adjacentguardrail sections 224. Beginning with the guardrail section 224 that isclosest to the sled 102, a portion of each guardrail section 224 coversover a portion of the front side 226 of the succeeding guardrail section224. The guardrail sections 224 are attached to the guardrail posts 104and at least the guardrail post 106 nearest to the guardrail posts 104by frangible fasteners such that the guardrail sections 224 willcollapse in a roughly telescoping fashion in the event that the energyfrom the impact of the vehicle is not completely dissipated before thesled 102 reaches the nearest guardrail post 104 and the sled 102 ispushed beyond the nearest guardrail post 104 by the impacting vehicle.Thus the spearing of the impacting vehicle by the guardrail sections 224is prevented. The cables 108, 110 should extend from about the groundanchor locations 116, 118 to at least the guardrail post 104 that isnearest the sled 102. In the illustrated example, the cables 108, 110extend from proximate the ground anchor locations 116, 118 to theguardrail post 104 that is nearest the sled 102 and continue to extendover the distance covered by the guardrail sections 224 that aresupported in whole or in part by the yieldable guardrail posts 104.Accordingly, the cables 108, 110 extend from proximate the ground anchorlocations 116, 118 to the guardrail post 106 that is nearest theguardrail posts 104.

The guardrail system 100 also includes a cable guide 322. The cableguide 322 includes a wedge-shaped cap 324 and two tubular sleeves 326,328. The cap 324 is made of sheet metal and has a wide end 330 and anarrow end 332 with the cap 324 tapering from the wide end to the narrowend. The wide end 330 of the cap 324 is dimensioned and configured tofit over the end nearest the sled 102 of the guardrail section 224nearest the sled 102, and the cap 324 is fixed to that end of thatguardrail section using nuts and bolts. With the cap 324 fixed to theend of the guardrail section, the sleeves 326, 328 will be in registrywith the interior of the valleys 238, 240, respectively, on the backside 228 of the guardrail nearest the sled 102. Accordingly, the cables108, 110 can be routed through the sleeves 326, 328, respectively, sothat the cables 108, 110 can be maintained in a close relationship tothe back side of the guardrail section 224 nearest the sled 102.

The guardrail system 100 is also provided with a protective sheet metalcovering 334 that covers the cable brakes 112, 114. The covering 334provides some measure of protection from the elements to the cablebrakes 112, 114.

The guardrail system 100 has the desirable feature that the cables 108,110 follows a non-tortuous path as they pass through the cable brakes112, 114. Subjecting the cables 108, 110 to extreme bends or changes indirection, particularly upon vehicle impact, can excessively strain thestrands in the cables 108, 110. Such excessive strain can lead to thefatigue and breakage of the strands, which would ultimately lead to thefraying of the cables 108, 110. The terminology “non-tortuous” as usedherein means that any bends at least in the portion of the cables 108,110 passing through the sled 102 and within at least six inches of thesled 102, as measured along the respective cable, form internal anglesthat are all greater than or equal to 100° and less than or equal to180°. More preferably the internal angles formed by any bends in theaforementioned portion of the cables 108, 110 are in the range ofgreater than or equal to 110° to less than or equal to 180°. Of course,the definition of “non-tortuous” includes the case where there are nobends in the aforementioned portion of the cables 108, 110. In theillustrated embodiments, the portion of the cables 108, 110 passingthrough the cable brake housings 124, 126 follow a substantiallystraight path, the only significant bend in this portion of each cableoccurring near the cable outlet 130 of each respective cable brakehousing 124, 126.

In cases were the bend is well defined, as in the illustrated examples,the internal angle formed by any bend in the cables 108, 110 should bereadily apparent. In cases where the cables may follow a curved paththrough the bend or bends, the angle formed by the bends is more complexto define. In such cases, a portion of a cable follows a “non-tortuous”path when there are no two points along the portion of the cable suchthat direction vectors corresponding to the direction of the centrallongitudinal axis t of the portion of the cable at each of the twopoints, respectively, that are both directed in the direction ofincreasing distance measured along the cable from a common origin pointthat is located outside the portion of cable in question and correspondsto a distance of zero along the cable, when translated while preservingtheir direction to be placed in tip to tail relationship define aninternal angle that is acute. In other words, for each and every point βwithin the cable portion 105 in question if the direction vector 107 ofthe cable at a selected end point a of the cable portion in question isplaced in tip to tale relationship with the direction vector 109 of thecable at the point β within the cable portion in question then the twovectors would define an obtuse internal angle θ. This of course requiresthat the two direction vectors are both directed in the direction ofincreasing distance measured along the cable from a common origin pointthat is located outside the portion of cable in question (see FIGS. 58and 59). The same preferred ranges of angles mentioned previously alsoapply to the internal angle θ defined when the direction vector of thecable at the selected end point a of the cable portion in question isplaced in tip to tale relationship with the direction vector of thecable 108, 110 at any point β within the cable portion 105.

An optional method for installing the guardrail system 100, provided asan example of final assembly and constructability, will now bedescribed. The guardrail is constructed in the normal except for theterminal portion of the guardrail. One or more, preferably several,guardrail posts 104 are fixed to the surface proximate the roadwayupstream of the last guardrail post 106 in relation to the direction offlow of traffic. The guardrail sections 224 are mounted to the guardrailposts 104, 106 such that at least all the distances between theguardrail posts are spanned by guardrail sections 224. The guardrailsections 224 should be mounted to one or more of the guardrail posts 106near the guardrail posts 104 with a mounting bracket 250 having thesleeves 252, 254. At those guardrail posts 104, 106 where the sleeves252, 254 are not required, a mounting bracket similar to the mountingbracket 250 but lacking the sleeves 252, 254 is used to attach theparticular guardrail section 224 to the guardrail post 104, 106. In theillustrated example, a mounting bracket 250 is used to attach theguardrail section 224 to the guardrail posts 106 nearest the guardrailposts 104. The cable guide 322 can now be fixed to the end of theguardrail section 224 that is farthest upstream of the other guardrailsections 224 in relation to the direction of the flow of traffic in thelane nearest the guardrail system 100, i.e. the guardrail section 224that is to eventually be the closest to the sled 102.

The guardrail posts 104, 106 are fixed to the surface proximate theroadway downstream of the sled 102 in relation to the direction of theflow of traffic in the lane nearest the guardrail system 100.Accordingly, the base 186 is fixed to the surface proximate the roadwayupstream of the guardrail posts 104, 106 in relation to the direction ofthe flow of traffic in the lane nearest the guardrail system 100.

The anchor structure 264 can then be fixed to the surface proximate theroadway upstream of the base 186 in relation to the direction of theflow of traffic. The base 186 and the anchor structure 264 may beprefabricated into a single assembly prior to being fixed to the surfaceproximate the roadway. The sled 102 can then be positioned atop the baseplate 188.

The shafts 246, 248 at the second ends of the cables 108, 110 are theninserted through the sleeves 252, 254 of the mounting bracket 250 thatis located farthest from the sled 102 and the nuts 260, 262 are engagedto the shafts 246, 248, respectively, to thereby anchor the second endsof the cables 108, 110 at an anchor location corresponding to thelocation of the mounting bracket 250 that is located farthest from thesled 102. The cables 108, 110 are then routed through the valleys 238,240 on the back side 228 of the guardrail sections 224 and through thesleeves 326, 328 of the cable guide 322. Each of the collars 144 is thenplaced around a respective one of the cables 108, 110 and then each ofthe cables 108, 110 is routed through the respective cable brake housing124, 126 of the sled 102. Thus the cables 108, 110 are routed throughthe sled 102. Each of the collars 144 is placed around a respective oneof the cables 108, 110 such that the first surface 154 of the collar 144faces away from the sled 102.

The shafts 280, 282 at the first ends of the cables 108, 110 are thenpositioned so as to extend through the slots 284, 286 in the angledplates 272, 274 and the nuts 288, 290 are engaged to the shafts 280,282, respectively, to thereby anchor the first ends of the cables 108,110 at an anchor location near the surface proximate the roadway andupstream of the sled 102 relative to the direction of traffic flow in alane of the road nearest the guardrail system 100. Accordingly, aportion of the cables 108, 110 extends between the sled 102 and theguardrail post 104 nearest the sled 102. The collars 144 are positionedintermediate the sled 102 and the cable guide 322.

Next a pair of brake pads 120, 122 are placed around the cable 108 suchthat the brake pads 120, 122 are positioned at least in part in thebrake housing 124. The collar 144 on cable 108 is then brought intocontact with the brake pads 120, 122 on either side of the cable 108,with the first surface 154 of the collar 144 facing away from the brakepads 120, 122. The pair of wedges 146, 148 of the cable brake 112 areeach positioned in contact with a respective sloping portion of thefirst surface 154 of the collar 144 on either side of the centerline ofthe first surface 154 of the collar 144. Each of the pair of bolts 150,152 of the cable brake 112 is positioned such that its shaft passesthrough the hole 170, 172 of the respective one of the pair of wedges146, 148 and the slot 162 of the collar 144 and engages a respective oneof the threaded holes 136, 140 of the first and second brake pads 120,122. The pair of bolts 150, 152 are tightened, with the head of each ofthe bolts being in contact with the respective one of the pair ofwedges, to force the first and second brake pads 120, 122 toward oneanother such that the cable 108 is clamped between the first and secondbrake pads 120, 122 of the cable brake 112, and thus frictional forcesbetween the cable 108 and the first and second brake pads 120, 122 ofthe cable brake 112 are set at a predetermined level.

Similarly, a pair of brake pads 120, 122 are placed around the cable 110such that the brake pads 120, 122 are positioned at least in part in thebrake housing 126. The collar 144 on cable 110 is then brought intocontact with the brake pads 120, 122 on either side of the cable 110,with the first surface 154 of the collar 144 facing away from the brakepads 120, 122. The pair of wedges 146, 148 of the cable brake 114 areeach positioned in contact with a respective sloping portion of thefirst surface 154 of the collar 144 on either side of the centerline ofthe first surface 154 of the collar 144. Each of the pair of bolts 150,152 of the cable brake 114 is positioned such that its shaft passesthrough the hole 170, 172 of the respective one of the pair of wedges146, 148 and the slot 162 of the collar 144 and engages a respective oneof the threaded holes 136, 140 of the first and second brake pads 120,122. The pair of bolts 150, 152 are tightened, with the head of each ofthe bolts being in contact with the respective one of the pair ofwedges, to force the first and second brake pads 120, 122 toward oneanother such that the cable 110 is clamped between the first and secondbrake pads 120, 122 of the cable brake 114, and thus frictional forcesbetween the cable 110 and the first and second brake pads 120, 122 ofthe cable brake 114 are set at a predetermined level.

In each of the cable brakes 112, 114, the pair of wedges 146, 148 arepositioned on opposite sides of the centerline of the first surface 154of the collar 144 with the respective cable 108, 110 passing between thepair of wedges 146, 148, and such that each of the pair of wedges 146,148 is placed in contact with the respective sloping portion of thefirst surface 154 of the collar 144 with its thick side being positionedcloser to the centerline of the first surface 154 of the collar than itsthin side. Thus, in operation the head of each of the pair of bolts 150,152 is in contact with a front surface of a respective one of the pairof wedges 146, 148 that is essentially perpendicular to the longitudinalaxis of the respective cable 108, 110.

Loosening the nuts 260, 262 and tightening the nuts 288, 290 moves thebrake pads 120, 122 of the cable brake 112 and the brake pads 120, 122of the cable brake 114 such that the brake pads 120, 122 of the cablebrake 112 and the brake pads 120, 122 of the cable brake 114 arepositioned snugly within the respective brake housings 124, 126.

Thus the brake pads 120, 122 of the cable brake 112 and the brake pads120, 122 of the cable brake 114 are frictionally engaged to the cables108, 110, respectively, with the brake pads 120, 122 of the cable brake112 and the brake pads 120, 122 of the cable brake 114 positionedrelative to the sled 102 such that the brake pads 120, 122 of the cablebrake 112 and the brake pads 120, 122 of the cable brake 114 wouldinterfere with movement of the sled 102 toward the guardrail post 104nearest the sled 102 over at least a substantial portion of a distancebetween the sled 102 and the nearest guardrail post 104 upon impact of avehicle on the sled 102.

Furthermore, the interference with the movement of the sled 102 towardthe nearest guardrail post 104 due to the engagement of the brake pads120, 122 of the cable brakes 112, 114 is of such a nature that the sled102 can move along the cables 108, 110 upon the impact of a vehicle onthe sled 102, when the vehicle impacts the sled 102 with energy above apredetermined threshold level, while the frictional forces between thecables 108, 110 and the brake pads 120, 122 of the cable brakes 112, 114dissipate at least a portion of the energy from the impact.

The distance between the sled 102 and the nearest yieldable post 104,the threshold impact energy level for overcoming the friction due to thecable brakes 112, 114, the number of yieldable guardrail posts 104 thatshould be used and the distance that they cover, can all be determinedby routine experimentation involving crash testing and taking intoaccount the applicable mandatory safety regulations and if necessary theaverage speed and weight of vehicles expected at a particular site.

Referring to FIGS. 33-36, a second embodiment 400 of the presentinvention can be seen. In the interest of brevity only the differencesbetween the guardrail systems 100 and 400 are discussed in detail. Inall other respects the guardrail systems 100 and 400 are identical. Inthe guardrail system 400 the guardrail sections 224 completely span thedistance between the sled 402 and the nearest guardrail post 404. Theguardrail posts 404 are wooden and are drilled at locations 403 and 405to make them frangible in a head-on collision of a vehicle with theterminal end of the guardrail system 400. The guardrail system 400 doesnot have a cable guide 322.

The sled 402 does not have a protective cover 334, and the sled 402lacks the catch member 202 and lever arm 206. The sled 402 is providedwith a fixed impact plate 522. The base plate 488 lacks any kind ofguide like guide 194. The sled 402, and consequently the skid plate 492,simply rests atop the base plate 488. The skid plate 492 has a forwardportion that is turned up in a manner resembling skis to prevent thesled 402 from digging into the ground and getting stuck after impact.

In the guardrail system 400 the angled plates 272, 274 are replaced bytubular structures 572, 574 that function in a manner similar to tubularsleeves 252, 254. The various components and features from the guardrailsystems 100 and 400 can be used in any combination to construct avariety of guardrail systems within the scope of the appended claims.

Referring to FIGS. 37-52, a releasable post 700 that can be substitutedfor the yieldable posts 104 can be seen. The releasable post 700includes a base 786, a beam 800, a skid plate 792, and a catch member802. In the illustrated example, the base 786 includes an elongated basepost 790 adapted for being buried at least in part below ground tothereby anchor the releasable post 700 to the ground. As discussedpreviously with respect to the base 186 and the posts 104, 106, the basepost 790 can be replaced by other structures depending on the nature ofthe surface to which the releasable post 700 is to be fixed. The base786 also includes a base plate 788 that is attached to the top of thebase post 790. In the illustrated example, the base plate 788 has asleeve 787 welded to its bottom surface. The sleeve 787 fits into thetop of the base post 790, and the sleeve 787 and the base post 790 eachhave one or more holes such that the holes of the sleeve 787 registerwith the holes of the base post 790 to allow pins, rivets, bolts or thelike to be used to attach the base plate to the base post 790.Alternatively, the base plate 788 can be directly welded to the top ofthe base post 790.

The skid plate 792 is attached to the lower end of the beam 800. Thecatch member 802 is pivotally attached to the beam 800 such that thecatch member 802 pivots about a pivot axis. The catch member 802 ispivotally movable between a raised position and a lowered position. Whenthe base post 790 is buried at least in part below ground and the beam800 is mounted on the base plate 788 with the skid plate 792 supportedby the base plate 788 and the catch member 802 is in the loweredposition, the catch member 802 has a portion that overlaps at least aportion of at least one of the base plate 788 and the base post 790 suchthat rectilinear movement of the beam 800 relative to the base post 790in a predetermined direction would essentially be prevented byinterference between the catch member 802 and at least one of the baseplate 788 and the base post 790. A lever arm 806 is attached to thecatch member 802. The catch member 802 is movable between the loweredposition and the raised position responsive to the lever arm 806 movingbetween a first position and a second position. The catch member 802moves toward the raised position as the lever arm 806 is moved towardthe second position which is closer to the beam 800 as compared to thefirst position.

When the catch member 802 is in the lowered position, an impact on thelever arm 806 that moves the lever arm 806 to the second position freesthe beam 800 for rectilinear motion relative to the base post 790 in thepredetermined direction. In most applications the predetermineddirection would be the same as the direction of on-coming traffic.

The catch member 802 is similar to the catch member 202 and the catchmember 802 includes two parallel plates 808, 810 that are spaced apartfrom one another and a catch plate 812 that extends between the parallelplates 808, 810. Each of the parallel plates 808, 810 is provided with ahole 814 and 816, respectively. The hole 814 of the first one of theparallel plates 808 is in registry with the hole 816 of the second oneof the parallel plates 810. Each hole 814, 816 in each parallel plate808, 810 is located at spaced separation from the catch plate 812. Oneor more shafts or pins 818 pass through one or more openings, there aretwo openings 820, 821 in the illustrated example, in the beam 800 andthrough each hole 814, 816 in each parallel plate 808, 810 to therebypivotally attach the catch member 802 to the beam 800. A bumper 822 ispreferably attached to the lever arm 806 to minimize damage to thereleasable post 700.

In the illustrated example, the base plate 788 is inclined such that itslopes upward in the predetermined direction when the base post 790 isburied at least in part below ground. The base plate 788 is providedwith a guide 794 that guides the skid plate 792 during the rectilinearmovement of the skid plate 792 relative to the base plate 788. All thesame types of guides 194 discussed in relation to the base plate 188 mayalso be used with the base plate 788. In the illustrated example, theguide 794 is in the form of a pocket 796 that receives a portion of theskid plate 792. The guardrail sections 224 can be attached to the beam800 in the same manner in which they are attached to the guardrail posts104 and 106.

The beams 200 and 800, the lever arms 206, 806, the skid plates 192 and792, the catch members 202 and 802, the impact plate 222, and the bumper822 may be provided with various slots, holes, or openings, for examplethe slots 824, 826, 828 and 830, as necessary to provide clearance forcables that may be part of the guardrail system in which thesecomponents are used.

In some applications it may be desirable to use washers between the nuts260, 262, 288, or 290 and the corresponding sleeves or angled plates.The washers may prevent damage to contact surfaces when the nuts aretightened, may provide greater surface area for better distribution offorces, and may be needed to enhance the size of the nuts where the nutsare smaller than would be desirable relative to the size of thecorresponding openings in the sleeves and angled plates.

It should be noted that the sled and cable brake system of the presentinvention can be used in conjunction with a variety of barrier systems.The sled and cable brake system of the present invention can be usedwith barriers in the form of corrugated metal beams including “W-Beam”or “Thrie-Beam” barriers such as shown in FIG. 1. The impact-absorbingsled and cable brake system of the present invention can be used withwire ripe cable barriers—tensioned or un-tensioned. The sled and cablebrake system of the present invention can be used with concrete barrierssuch as bridge parapets, piers or columns. In the case of use withconcrete barriers, the cable guide 322 and mounting bracket 250 wouldhave to be modified accordingly in order to attach or anchor the cables108, 110 to the particular concrete barrier.

It is to be understood that the present invention is not limited to theembodiments described above, but encompasses any and all embodimentswithin the scope of the following claims.

1. An impact absorbing system for use with a barrier positionedproximate a pathway for use by vehicular traffic, the impact absorbingsystem comprising: a sled; at least one cable having a portion extendingbetween the barrier and said sled and a portion extending between saidsled and a first anchor location proximate the pathway, in use said sledbeing positioned between the barrier and said first anchor location; anda cable brake supported by said sled, wherein a portion of said cablepassing through said sled and extending at least six inches on eitherside of said sled follows a non-tortuous path, whereby when the impactabsorbing system is installed proximate the pathway, said sled can movealong said cable upon impact of a vehicle on said sled, the vehicleimpacting said sled with energy, and with frictional forces between saidcable and said cable brake dissipating at least a portion of the energyfrom the impact.
 2. The impact absorbing system of claim 1, wherein foreach and every point within said portion of said cable passing throughsaid sled and extending at least six inches on either side of said sledif a direction vector of said cable at a selected end point of saidportion of said cable is placed in tip to tale relationship with adirection vector of said cable at a point within said portion of saidcable then said direction vector of said cable at said selected endpoint and said direction vector of said cable at said point within saidportion of said cable define an internal angle in the range of 100° to180°.
 3. The impact absorbing system of claim 1, wherein internal anglesformed by any bends in said portion of said cable passing through saidsled and extending at least six inches on either side of said sled arein the range of greater than or equal to 100° to less than or equal to180°.
 4. The impact absorbing system of claim 1, wherein internal anglesformed by any bends in said portion of said cable passing through saidsled and extending at least six inches on either side of said sled arein the range of greater than or equal to 110° to less than or equal to180°.
 5. A guardrail system having an impact absorbing terminal portioncomprising: a sled according to claim 1; a barrier comprising at leastone guardrail post adapted for being fixed to a surface proximate aroadway; at least one cable having a portion extending between saidguardrail post and said sled and a portion extending between said sledand a first anchor location near the surface proximate the roadway, inuse said sled being positioned between said guardrail post and saidfirst anchor location; and a cable brake supported by said sled, saidcable brake comprising at least a first brake pad and a second brake padpositioned on opposite sides of said cable, said first brake pad andsaid second brake pad frictionally engaging said cable in use, wherebywhen the guardrail system is installed on a side of the roadway, saidsled can move along said cable upon impact of a vehicle on said sled,the vehicle impacting said sled with energy, with frictional forcesbetween said cable and said first and second brake pads dissipating atleast a portion of the energy from the impact.
 6. The guardrail systemof claim 5, wherein said cable brake further comprises a cable brakehousing incorporated in said sled, and wherein said first brake pad andsaid second brake pad are received in said cable brake housing.
 7. Theguardrail system of claim 6, wherein said cable brake housing has acable inlet, cable outlet, and opposing sidewall portions that aretapering from said cable inlet to said cable outlet such that saidopposing sidewall portions are closer together near said cable outlet ascompared to said opposing sidewall portions near said cable inletwhereby as said sled moves along said cable upon impact of a vehicle onsaid sled, said tapering opposing sidewall portions tend to moreforcefully squeeze said first and second brake pads toward one anothersuch that said frictional forces between said cable and said first andsecond brake pads are increased.
 8. The guardrail system of claim 7,wherein said first brake pad has a threaded hole provided at a locationthat is at spaced separation from a surface portion of said first brakepad that is in contact with said cable when in use, wherein said secondbrake pad has a threaded hole provided at a location that is at spacedseparation from a surface portion of said second brake pad that is incontact with said cable when in use, and wherein said cable brakefurther comprises: a collar having a first surface facing away from saidfirst and second brake pads when said cable brake is fully assembled,said first surface of said collar declining from either side of saidcollar toward a centerline of said first surface of said collar suchthat said centerline of said first surface of said collar is depressedrelative to either side of said first surface of said collar with saidfirst surface of said collar sloping forward on either side of saidcenterline, said collar having an elongated slot extending on eitherside of said centerline, a pair of bolts each having a head and a shaftthat is threaded at least in part; and a pair of wedges each having ahole that is sized to provide clearance for said shaft of a respectiveone of said pair of bolts and said slot being sized to provide clearancefor said shaft of each of said pair of bolts and said cable such thatsaid shaft of each of said pair of bolts can pass through said hole of arespective one of said pair of wedges and said slot to engage arespective one of said threaded hole of said first brake pad and saidthreaded hole of said second brake pad, wherein when each of said pairof wedges is positioned in contact with a respective sloping portion ofsaid first surface of said collar on either side of said centerline ofsaid first surface of said collar, and when each of said pair of boltsis positioned such that its shaft passes through said hole of saidrespective one of said pair of wedges and said slot and engages arespective one of said threaded hole of said first brake pad and saidthreaded hole of said second brake pad, tightening said pair of boltswith said head of each of said bolts being in contact with saidrespective one of said pair of wedges tends to force said first andsecond brake pads toward one another such that frictional forces betweensaid cable and said first and second brake pads are increased.
 9. Theguardrail system according to claim 8, wherein said cable has alongitudinal axis, wherein each of said pair of wedges has a thick sideand a thin side, wherein said pair of wedges are positioned on oppositesides of said centerline of said first surface of said collar with saidcable passing between said pair of wedges, and wherein each of said pairof wedges is placed in contact with said respective sloping portion ofsaid first surface of said collar with its thick side being positionedcloser to said centerline of said first surface of said collar than itsthin side such that in operation said head of each of said pair of boltsis in contact with a front surface of a respective one of said pair ofwedges that is essentially perpendicular to said longitudinal axis ofsaid cable.
 10. The guardrail system according to claim 9, wherein saidslot has a widened middle portion through which said cable passes inoperation, said widened middle portion having an outline that follows acircular arc on either side of said slot.
 11. The guardrail systemaccording to claim 5, wherein the guardrail system comprises a baseadapted for being fixed to the surface proximate the roadway, whereinsaid base comprises a base plate, and wherein said sled furthercomprises at least one skid plate capable of being supported on top ofsaid base plate for essentially rectilinear movement parallel to saidbase plate upon impact of the vehicle on said sled.
 12. The guardrailsystem according to claim 11, wherein when in use said base plate isinclined such that it slopes upward in the direction of oncomingtraffic.
 13. The guardrail system according to claim 11, wherein saidbase plate is provided with a guide that guides said skid plate duringsaid rectilinear movement of said skid plate relative to said baseplate.
 14. The guardrail system according to claim 13, wherein saidguide is in the form of a channel that receives a portion of said skidplate.
 15. The guardrail system according to claim 13, wherein saidguide is in the form of opposing channels on either side of said baseplate that receive portions of said skid plate on either side of saidskid plate.
 16. The guardrail system according to claim 13, wherein saidguide is in the form of a pocket that receives a portion of said skidplate.
 17. The guardrail system according to claim 11, wherein said sledfurther comprises a beam, said beam has a lower end, said beam supportssaid cable brake housing and said skid plate is attached to said beam atsaid lower end of said beam.
 18. The guardrail system according to claim17, further comprising a catch member pivotally attached to said beamsuch that said catch member pivots about a horizontal pivot axis, saidcatch member being pivotally movable between a raised position and alowered position, when said sled is mounted on said base with said catchmember positioned substantially on the side of said beam that facestoward oncoming traffic and with said catch member in the loweredposition, said catch member has a portion that overlaps at least aportion of said base as seen from the view of oncoming traffic such thatmovement of said sled relative to said base in the same direction asoncoming traffic would essentially be prevented by interference betweensaid catch member and said base.
 19. The guardrail system according toclaim 18, further comprising a lever arm attached to said catch member,said catch member being movable between said lowered position and saidraised position responsive to said lever arm moving between a firstposition and a second position such that said catch member moves towardsaid raised position as said lever arm is moved toward said secondposition which is closer to said beam compared to said first position,whereby when said sled is mounted on said base with said catch memberpositioned substantially on the side of said beam that faces towardoncoming traffic and with said catch member in the lowered position andwith said cable being in engagement with said cable brake, said leverarm is moved to said second position by a vehicle in the process ofcolliding with said sled before the vehicle has an impact upon said sledto thereby free said sled for rectilinear motion relative to said basesuch that said sled can move relative to said base due to the impactenergy imparted to said sled by the vehicle and gradually slow down thevehicle.
 20. The guardrail system according to claim 19, wherein saidcatch member comprises two parallel plates that are spaced apart fromone another and a catch plate extending between said parallel plates,each of said parallel plates being provided with a hole and with saidhole of a first one of said parallel plates being in registry with saidhole of a second one of said parallel plates, wherein each said hole ineach of said parallel plates is located at spaced separation from saidcatch plate, wherein the guardrail system further comprises a shaftpassing through an opening in said beam and through each said hole ineach of said parallel plates to thereby pivotally attach said catchmember to said beam, and wherein when said sled is mounted on said basewith said catch member positioned substantially on the side of said beamthat faces toward oncoming traffic and with said catch member in thelowered position, a portion of said catch plate overlaps at least aportion of said base as seen from the view of oncoming traffic such thatmovement of said sled relative to said base in the same direction asoncoming traffic would essentially be prevented by interference betweensaid catch member and said base.
 21. The guardrail system according toclaim 11, further comprising a catch member pivotally attached to saidsled such that said catch member pivots about a horizontal pivot axis,said catch member being pivotally movable between a raised position anda lowered position, when said sled is mounted on said base with saidcatch member positioned substantially on the side of said sled thatfaces toward oncoming traffic and with said catch member in the loweredposition, said catch member has a portion that overlaps at least aportion of said base as seen from the view of oncoming traffic such thatmovement of said sled relative to said base in the same direction asoncoming traffic would essentially be prevented by interference betweensaid catch member and said base.
 22. The guardrail system according toclaim 21, further comprising a lever arm attached to said catch member,said catch member being movable between said lowered position and saidraised position responsive to said lever arm moving between a firstposition and a second position such that said catch member moves towardsaid raised position as said lever arm is moved toward said secondposition which is closer to said brake housing compared to said firstposition, whereby when said sled is mounted on said base with said catchmember positioned substantially on the side of said sled that facestoward oncoming traffic and with said catch member in the loweredposition and with said cable being in engagement with said cable brake,said lever arm is moved to said second position by a vehicle in theprocess of colliding with said sled before the vehicle has an impactupon said sled to thereby free said sled for rectilinear motion relativeto said base such that said sled can move relative to said base due tothe impact energy imparted to said sled by the vehicle and graduallyslow down the vehicle.
 23. The guardrail system according to claim 22,further comprising an impact plate attached to said lever arm.
 24. Theguardrail system according to claim 21, wherein said catch membercomprises two parallel plates that are spaced apart from one another anda catch plate extending between said parallel plates, each of saidparallel plates being provided with a hole and with said hole of a firstone of said parallel plates being in registry with said hole of a secondone of said parallel plates, wherein each said hole in each of saidparallel plates is located at spaced separation from said catch plate,wherein the guardrail system further comprises a shaft passing throughan opening in said sled and through each said hole in each of saidparallel plates to thereby pivotally attach said catch member to saidsled, and wherein when said sled is mounted on said base with said catchmember positioned substantially on the side of said sled that facestoward oncoming traffic and with said catch member in the loweredposition, a portion of said catch plate overlaps at least a portion ofsaid base as seen from the view of oncoming traffic such that movementof said sled relative to said base in the same direction as oncomingtraffic would essentially be prevented by interference between saidcatch member and said base.
 25. The guardrail system according to claim24, further comprising a lever arm attached to said catch member, saidcatch member being movable between said lowered position and said raisedposition responsive to said lever arm moving between a first positionand a second position such that said catch member moves toward saidraised position as said lever arm is moved toward said second positionwhich is closer to said brake housing compared to said first position,whereby when said sled is mounted on said base with said catch memberpositioned substantially on the side of said sled that faces towardoncoming traffic and with said catch member in the lowered position andwith said cable being in engagement with said cable brake, said leverarm is moved to said second position by a vehicle in the process ofcolliding with said sled before the vehicle has an impact upon said sledto thereby free said sled for rectilinear motion relative to said basesuch that said sled can move relative to said base due to the impactenergy imparted to said sled by the vehicle and gradually slow down thevehicle.
 26. The guardrail system according to claim 25, furthercomprising an impact plate attached to said lever arm.
 27. The guardrailsystem according to claim 11, wherein the guardrail system furthercomprises at least one guardrail section, wherein said guardrail sectionhas a front side and a back side, wherein said cable has a first end anda second end, said first end of said cable is anchored to the surfaceproximate the roadway at said first anchor location and said second endof said cable is anchored in place at a second anchor location over saidback side of said guardrail section, when the guardrail system isinstalled on the side of the roadway.
 28. The guardrail system accordingto claim 27, wherein said guardrail section is one of a plurality ofguardrail sections included in the guardrail system, wherein at leastone of said plurality of guardrail sections is supported at least inpart by said guardrail post, wherein each of said plurality of guardrailsections has a front side, a back side, and a cross sectional shape thatprovides at least one trough on said back side of each of said pluralityof guardrail sections, and wherein said second end of said cable isanchored in position in said trough of one of said plurality ofguardrail sections, when the guardrail system is installed on the sideof the roadway.
 29. The guardrail system according to claim 28, whereinsaid second end of said cable is provided with a threaded shaft that isessentially coaxial with said cable and the guardrail system furthercomprises: a mounting bracket for attaching one of said plurality ofguardrail sections to said guardrail post, wherein said mounting bracketincludes at least one sleeve having a bore with a diameter that is largeenough to allow said threaded shaft to extend through said bore of saidsleeve; and a threaded nut capable of engaging said threaded shaft, saidnut being too large to pass through said bore of said sleeve, said nutengaging said threaded shaft with said cable extending toward said sledon an opposite side of said sleeve relative to said nut to therebyanchor said second end of said cable in position over said back side ofone of said plurality of guardrail sections, when said threaded nut isengaged to said threaded shaft and the guardrail system is installed onthe side of the roadway.
 30. The guardrail system according to claim 27,wherein said guardrail section is supported at least in part by saidguardrail post, wherein said guardrail section has a cross sectionalshape that provides at least one trough on said back side of saidguardrail section, and wherein said second end of said cable is anchoredin position in said trough of said guardrail section, when the guardrailsystem is installed on the side of the roadway.
 31. The guardrail systemaccording to claim 30, wherein said second end of said cable is providedwith a threaded shaft that is essentially coaxial with said cable andthe guardrail system further comprises: a mounting bracket for attachingsaid guardrail section to said guardrail post, wherein said mountingbracket includes at least one sleeve having a bore with a diameter thatis large enough to allow said threaded shaft to extend through said boreof said sleeve; and a threaded nut capable of engaging said threadedshaft, said nut being too large to pass through said bore of saidsleeve, said nut engaging said threaded shaft with said cable extendingtoward said sled on an opposite side of said sleeve relative to said nutto thereby anchor said second end of said cable in position over saidback side of said guardrail section, when said threaded nut is engagedto said threaded shaft and the guardrail system is installed on the sideof the roadway.
 32. The guardrail system according to claim 31, whereinsaid base has a base post adapted for being fixed to the surfaceproximate the roadway to thereby anchor said base to the surfaceproximate the roadway, wherein said base post has a top, and whereinsaid base plate is attached to said top of said base post, the guardrailsystem further comprising: an anchor structure for anchoring said firstend of said cable to the surface proximate the roadway at said firstanchor location when the guardrail system is installed on a side of theroadway.
 33. The guardrail system according to claim 32, wherein saidthreaded nut is a first threaded nut and said threaded shaft is a firstthreaded shaft, wherein said first end of said cable is provided with asecond threaded shaft that is essentially coaxial with said cable andsaid anchor structure comprises: an anchor post adapted for being fixedto the surface proximate the roadway, in use said anchor post beingpositioned upstream of said base post relative to the direction oftraffic flow in a lane of the roadway nearest the guardrail system; apair of bars extending in parallel between said anchor post and saidbase post, each of said pair of bars having a longitudinal axis, each ofsaid pair of bars having a first end and a second end, each of said pairof bars being attached to said anchor post proximate said first endthereof, and each of said pair of bars being attached to said base postproximate said second end thereof; at least one angled plate extendingbetween said pair of bars at a position intermediate said anchor postand said base post, said angled plate having an inclined portion that isangled relative to said longitudinal axis of each of said pair of barssuch that in use said inclined portion rises upward relative to thesurface proximate the roadway with decreasing horizontal distance fromsaid anchor post, said inclined portion having an opening that is largeenough to allow said second threaded shaft at said first end of saidcable to extend through said opening of said inclined portion; and asecond threaded nut capable of engaging said second threaded shaft atsaid first end of said cable, said second threaded nut being too largeto pass through said opening of said inclined portion, said second nutengaging said second threaded shaft at said first end of said cable withsaid cable extending toward said sled on an opposite side of saidinclined portion relative to said second nut to thereby anchor saidfirst end of said cable in position at said first anchor location, whensaid second threaded nut is engaged to said second threaded shaft atsaid first end of said cable and the guardrail system is installed onthe side of the roadway.
 34. The guardrail system according to claim 33,wherein said opening in said inclined portion is in the form of aU-shaped slot.
 35. The guardrail system according to claim 33, whereinsaid cable is a first cable, said cable brake is a first cable brake,said sleeve is a first sleeve, and said angled plate is a first angledplate, wherein said mounting bracket includes a second sleeve, and theguardrail system further comprises: a second cable provided to extendsubstantially in parallel with said first cable, said second cablehaving a first end and a second end, wherein said second end of saidsecond cable is provided with a third threaded shaft that is essentiallycoaxial with said second cable, wherein said first end of said secondcable is provided with a fourth threaded shaft that is essentiallycoaxial with said second cable, wherein said second sleeve has a borewith a diameter that is large enough to allow said third threaded shaftto extend through said bore of said second sleeve; a second cable brakesupported by said sled, said second cable brake comprising at least athird brake pad and a fourth brake pad positioned on opposite sides ofsaid second cable, said third brake pad and said fourth brake padfrictionally engaging said second cable in use; a third threaded nutcapable of engaging said third threaded shaft, said third threaded nutbeing too large to pass through said bore of said second sleeve, saidthird threaded nut engaging said third threaded shaft with said secondcable extending toward said sled on an opposite side of said secondsleeve relative to said third threaded nut to thereby anchor said secondend of said second cable in position over said back side of saidguardrail section, when said third threaded nut is engaged to said thirdthreaded shaft and the guardrail system is installed on the side of theroadway; a second angled plate extending between said pair of bars at aposition intermediate said first angled plate and one of said anchorpost and said base post, said second angled plate having an inclinedportion that is angled relative to said longitudinal axis of each ofsaid pair of bars such that in use said inclined portion of said secondangled plate rises upward relative to the surface proximate the roadwaywith decreasing horizontal distance from said anchor post, said inclinedportion of said second angled plate having an opening that is largeenough to allow said fourth threaded shaft at said first end of saidsecond cable to extend through said opening of said inclined portion ofsaid second angled plate; and a fourth threaded nut capable of engagingsaid fourth threaded shaft at said first end of said second cable, saidfourth threaded nut being too large to pass through said opening of saidinclined portion of said second angled plate, said fourth threaded nutengaging said fourth threaded shaft at said first end of said secondcable with said second cable extending toward said sled on an oppositeside of said inclined portion of said second angled plate relative tosaid fourth threaded nut to thereby anchor said first end of said secondcable in position at a third anchor location, when said fourth threadednut is engaged to said fourth threaded shaft at said first end of saidsecond cable and the guardrail system is installed on the side of theroadway.
 36. The guardrail system of claim 35, wherein said guardrailpost is a yieldable guardrail post designed to yield at a predeterminedimpact force, said yieldable guardrail post comprising: a firstelongated member having an elongated back plate and two side plates thatare parallel two one another, said side plates projecting at rightangles to said back plate on either side of said back plate to therebygive said first elongated member a channel-shaped cross section; asecond elongated member having an elongated back plate and two sideplates that are parallel two one another, said side plates of saidsecond elongated member projecting at right angles to said back plate ofsaid second elongated member on either side of said back plate of saidsecond elongated member to thereby give said second elongated member achannel-shaped cross section, said first elongated member and saidsecond elongated member being attached together with their respectiveback plates in abutting contact so as to form a beam having an H-shapedcross section, said first and second elongated members each having alongitudinal axis, said second elongated member having a slit transverseto said longitudinal axis thereof that transects said second elongatedmember; and a reinforcement plate attached to said back plate of one ofsaid first elongated member and said second elongated member proximatesaid slit in each of said side plates of said second elongated member.37. The guardrail system according to claim 29, wherein said base has abase post adapted for being fixed to the surface proximate the roadwayto thereby anchor said base to the surface proximate the roadway,wherein said base post has a top, and wherein said base plate isattached to said top of said base post, the guardrail system furthercomprising: an anchor structure for anchoring said first end of saidcable to the surface proximate the roadway at said first anchor locationwhen the guardrail system is installed on the side of the roadway. 38.The guardrail system according to claim 37, wherein said threaded nut isa first threaded nut and said threaded shaft is a first threaded shaft,wherein said first end of said cable is provided with a second threadedshaft that is essentially coaxial with said cable and said anchorstructure comprises: an anchor post adapted for being fixed to thesurface proximate the roadway, in use said anchor post being positionedupstream of said base post relative to the direction of traffic flow ina lane of the roadway nearest the guardrail system; a pair of barsextending in parallel between said anchor post and said base post, eachof said pair of bars having a longitudinal axis, each of said pair ofbars having a first end and a second end, each of said pair of barsbeing attached to said anchor post proximate said first end thereof, andeach of said pair of bars being attached to said base post proximatesaid second end thereof; at least one angled plate extending betweensaid pair of bars at a position intermediate said anchor post and saidbase post, said angled plate having an inclined portion that is angledrelative to said longitudinal axis of each of said pair of bars suchthat in use said inclined portion rises upward relative to the surfaceproximate the roadway with decreasing horizontal distance from saidanchor post, said inclined portion having an opening that is largeenough to allow said second threaded shaft at said first end of saidcable to extend through said opening of said inclined portion; and asecond threaded nut capable of engaging said second threaded shaft atsaid first end of said cable, said second threaded nut being too largeto pass through said opening of said inclined portion, said second nutengaging said second threaded shaft at said first end of said cable withsaid cable extending toward said sled on an opposite side of saidinclined portion relative to said second nut to thereby anchor saidfirst end of said cable in position at said first anchor location, whensaid second threaded nut is engaged to said second threaded shaft atsaid first end of said cable and the guardrail system is installed onthe side of the roadway.
 39. The guardrail system according to claim 38,wherein said opening in said inclined portion is in the form of aU-shaped slot.
 40. The guardrail system according to claim 38, whereinsaid cable is a first cable, said cable brake is a first cable brake,said sleeve is a first sleeve, and said angled plate is a first angledplate, wherein said mounting bracket includes a second sleeve, and theguardrail system further comprises: a second cable provided to extendsubstantially in parallel with said first cable, said second cablehaving a first end and a second end, wherein said second end of saidsecond cable is provided with a third threaded shaft that is essentiallycoaxial with said second cable, wherein said first end of said secondcable is provided with a fourth threaded shaft that is essentiallycoaxial with said second cable, wherein said second sleeve has a borewith a diameter that is large enough to allow said third threaded shaftto extend through said bore of said second sleeve; a second cable brakesupported by said sled, said second cable brake comprising at least athird brake pad and a fourth brake pad positioned on opposite sides ofsaid second cable, said third brake pad and said fourth brake padfrictionally engaging said second cable in use; a third threaded nutcapable of engaging said third threaded shaft, said third threaded nutbeing too large to pass through said bore of said second sleeve, saidthird threaded nut engaging said third threaded shaft with said secondcable extending toward said sled on an opposite side of said secondsleeve relative to said third threaded nut to thereby anchor said secondend of said second cable in position over said back side of said one ofsaid plurality of guardrail sections, when said third threaded nut isengaged to said third threaded shaft and the guardrail system isinstalled on the side of the roadway; a second angled plate extendingbetween said pair of bars at a position intermediate said first angledplate and one of said anchor post and said base post, said second angledplate having an inclined portion that is angled relative to saidlongitudinal axis of each of said pair of bars such that in use saidinclined portion of said second angled plate rises upward relative tothe surface proximate the roadway with decreasing horizontal distancefrom said anchor post, said inclined portion of said second angled platehaving an opening that is large enough to allow said fourth threadedshaft at said first end of said second cable to extend through saidopening of said inclined portion of said second angled plate; and afourth threaded nut capable of engaging said fourth threaded shaft atsaid first end of said second cable, said fourth threaded nut being toolarge to pass through said opening of said inclined portion of saidsecond angled plate, said fourth threaded nut engaging said fourththreaded shaft at said first end of said second cable with said secondcable extending toward said sled on an opposite side of said inclinedportion of said second angled plate relative to said fourth threaded nutto thereby anchor said first end of said second cable in position at athird anchor location, when said fourth threaded nut is engaged to saidfourth threaded shaft at said first end of said second cable and theguardrail system is installed on the side of the roadway.
 41. Theguardrail system of claim 40, wherein said guardrail post is a yieldableguardrail post designed to yield at a predetermined impact force, saidyieldable guardrail post comprising: a first elongated member having anelongated back plate and two side plates that are parallel two oneanother, said side plates projecting at right angles to said back plateon either side of said back plate to thereby give said first elongatedmember a channel-shaped cross section; a second elongated member havingan elongated back plate and two side plates that are parallel two oneanother, said side plates of said second elongated member projecting atright angles to said back plate of said second elongated member oneither side of said back plate of said second elongated member tothereby give said second elongated member a channel-shaped crosssection, said first elongated member and said second elongated memberbeing attached together with their respective back plates in abuttingcontact so as to form a beam having an H-shaped cross section, saidfirst and second elongated members each having a longitudinal axis, saidsecond elongated member having a slit transverse to said longitudinalaxis thereof that transects said second elongated member; and areinforcement plate attached to said back plate of one of said firstelongated member and said second elongated member proximate said slit ineach of said side plates of said second elongated member.
 42. Theguardrail system of claim 5, wherein said guardrail post is a yieldableguardrail post designed to yield at a predetermined impact force, saidyieldable guardrail post comprising: a first elongated member having anelongated back plate and two side plates that are parallel two oneanother, said side plates projecting at right angles to said back plateon either side of said back plate to thereby give said first elongatedmember a channel-shaped cross section; a second elongated member havingan elongated back plate and two side plates that are parallel two oneanother, said side plates of said second elongated member projecting atright angles to said back plate of said second elongated member oneither side of said back plate of said second elongated member tothereby give said second elongated member a channel-shaped crosssection, said first elongated member and said second elongated memberbeing attached together with their respective back plates in abuttingcontact so as to form a beam having an H-shaped cross section, saidfirst and second elongated members each having a longitudinal axis, saidsecond elongated member having a slit transverse to said longitudinalaxis thereof that transects said second elongated member; and areinforcement plate attached to said back plate of one of said firstelongated member and said second elongated member proximate said slit ineach of said side plates of said second elongated member.
 43. Ayieldable guardrail post designed to yield at a predetermined impactforce, said yieldable guardrail post comprising: a first elongatedmember having an elongated back plate and two side plates that areparallel two one another, said side plates projecting at right angles tosaid back plate on either side of said back plate to thereby give saidfirst elongated member a channel-shaped cross section; a secondelongated member having an elongated back plate and two side plates thatare parallel two one another, said side plates of said second elongatedmember projecting at right angles to said back plate of said secondelongated member on either side of said back plate of said secondelongated member to thereby give said second elongated member achannel-shaped cross section, said first elongated member and saidsecond elongated member being attached together with their respectiveback plates in abutting contact so as to form a beam having an H-shapedcross section, said first and second elongated members each having alongitudinal axis, said second elongated member having a slit transverseto said longitudinal axis thereof that transects said second elongatedmember; and a reinforcement plate attached to said back plate of one ofsaid first elongated member and said second elongated member proximatesaid slit in each of said side plates of said second elongated member.44. A releasable post comprising: a base post adapted for being fixed toa surface to thereby anchor the releasable post to the surface, whereinsaid base post has a top; a base plate attached to said top of said basepost; a beam having a lower end; a skid plate attached to said beam atsaid lower end of said beam; a catch member pivotally attached to saidbeam such that said catch member pivots about a pivot axis, said catchmember being pivotally movable between a raised position and a loweredposition, when said base post is fixed to the surface, said beam ismounted on said base plate with said skid plate supported by said baseplate, and said catch member is in said lowered position, said catchmember has a portion that overlaps at least a portion of at least one ofsaid base plate and said base post such that rectilinear movement ofsaid beam relative to said base post in a predetermined direction wouldessentially be prevented by interference between said catch member andat least one of said base plate and said base post; and a lever armattached to said catch member, said catch member being movable betweensaid lowered position and said raised position responsive to said leverarm moving between a first position and a second position such that saidcatch member moves toward said raised position as said lever arm ismoved toward said second position which is closer to said beam comparedto said first position, whereby when said base post is fixed to thesurface, said beam is mounted on said base plate with said skid platesupported by said base plate, and said catch member is in said loweredposition, an impact on said lever arm that moves said lever arm to saidsecond position frees said beam for rectilinear motion relative to saidbase post in said predetermined direction.
 45. The releasable postaccording to claim 44, wherein said catch member comprises two parallelplates that are spaced apart from one another and a catch plateextending between said parallel plates, each of said parallel platesbeing provided with a hole and with said hole of a first one of saidparallel plates being in registry with said hole of a second one of saidparallel plates, wherein each said hole in each of said parallel platesis located at spaced separation from said catch plate, wherein thereleasable post further comprises a shaft passing through an opening insaid beam and through each said hole in each of said parallel plates tothereby pivotally attach said catch member to said beam, and whereinwhen said base post is fixed to the surface, said beam is mounted onsaid base plate with said skid plate supported by said base plate, andsaid catch member is in said lowered position, a portion of said catchplate overlaps at least a portion of at least one of said base plate andsaid base post such that rectilinear movement of said beam relative tosaid base post in said predetermined direction would essentially beprevented by interference between said catch member and at least one ofsaid base plate and said base post.
 46. The releasable post according toclaim 45, wherein said base plate is inclined such that it slopes upwardin said predetermined direction when said base post is fixed to thesurface.
 47. The releasable post according to claim 45, wherein saidbase plate is provided with a guide that guides said skid plate duringsaid rectilinear movement of said skid plate relative to said baseplate.
 48. The releasable post according to claim 47, wherein said guideis in the form of a channel that receives a portion of said skid plate.49. The releasable post according to claim 47, wherein said guide is inthe form of opposing channels on either side of said base plate thatreceive portions of said skid plate on either side of said skid plate.50. The releasable post according to claim 47, wherein said guide is inthe form of a pocket that receives a portion of said skid plate.
 51. Aguardrail system having an impact absorbing terminal portion comprising:a sled; a guardrail post adapted for being fixed to a surface proximatea roadway; at least one cable having a portion extending between saidguardrail post and said sled and a portion extending between said sledand a first anchor location, in use said sled being positioned betweensaid guardrail post and said first anchor location; and a cable brakesupported by said sled, said cable brake frictionally engaging saidcable in use, wherein a portion of said cable passing through said cablebrake follows a non-tortuous path, whereby when the guardrail system isinstalled on a side of the roadway, said sled can move along said cableupon impact of a vehicle on said sled, the vehicle impacting said sledwith energy, with frictional forces between said cable and said firstand second brake pads dissipating at least a portion of the energy fromthe impact.
 52. The guardrail system of claim 51, wherein said portionof said cable passing through said cable brake has bends such thatinternal angles formed by said bends of said portion of said cablepassing through said cable brake are all obtuse.
 53. The guardrailsystem of claim 52, wherein said internal angles formed by said bends ofsaid portion of said cable passing through said cable brake are in therange of greater than or equal to 110° to less than or equal to 180°.54. The guardrail system of claim 51, wherein said portion of said cablepassing through said cable brake follows a substantially straight path.55. A method for providing a guardrail system having an impact absorbingterminal portion on a surface proximate a roadway, the roadway having alane nearest the guardrail system, traffic in the lane nearest theguardrail system defining a direct of flow of traffic, the methodcomprising the steps of: providing a base adapted for being fixed to thesurface proximate the roadway, the base having a base plate; fixing thebase to the surface proximate the roadway; providing at least oneguardrail post adapted for being fixed to the surface proximate theroadway; fixing the guardrail post to the surface proximate the roadwaydownstream of the base in relation to the direction of flow of traffic;providing an anchor structure; fixing the anchor structure to thesurface proximate the roadway upstream of the base in relation to thedirection of flow of traffic; providing a sled; positioning the sled onthe base plate; providing at least one cable having a first end and asecond end; anchoring the first end of the cable to the anchor structureat a first anchor location upstream of the sled in relation to thedirection of flow of traffic; routing the cable through the sled;anchoring the second end of the cable at a second anchor locationdownstream of the sled in relation to the direction of flow of traffic,such that a portion of the cable extends between the guardrail post andthe sled; providing a cable brake comprising at least a first brake padand a second brake pad; and frictionally engaging the first brake padand the second brake pad to the cable with the first brake pad and thesecond brake pad positioned on opposite sides of the cable and with thefirst brake pad and the second brake pad positioned relative to the sledsuch that the first brake pad and the second brake pad would interferewith movement of the sled toward the guardrail post over at least asubstantial portion of a distance between the sled and the guardrailpost upon impact of a vehicle on the sled, and interference with themovement of the sled toward the guardrail post due to the engagement ofthe first brake pad and the second brake pad with the cable being ofsuch a nature that the sled can move along the cable upon the impact ofthe vehicle on the sled, when the vehicle impacts the sled with energyabove a predetermined threshold level, with frictional forces betweenthe cable and the first and second brake pads dissipating at least aportion of the energy from the impact.
 56. The method of claim 55,wherein the cable brake further comprises a cable brake housingincorporated in the sled, and wherein said step of frictionally engagingthe first brake pad and the second brake pad to the cable comprises thestep of positioning the first brake pad and the second brake pad suchthat the first brake pad and the second brake pad are received in thecable brake housing.
 57. The method of claim 56, further comprising thestep of providing the cable brake housing with a cable inlet, a cableoutlet, and opposing sidewall portions that are tapering from the cableinlet to the cable outlet such that the opposing sidewall portions arecloser together near the cable outlet as compared to the opposingsidewall portions near the cable inlet.
 58. The method of claim 55,further comprising the steps of: providing the first brake pad with athreaded hole at a location that is at spaced separation from a surfaceportion of the first brake pad that is in contact with the cable when inuse; providing the second brake pad with a threaded hole at a locationthat is at spaced separation from a surface portion of the second brakepad that is in contact with the cable when in use; providing a collarhaving a first surface facing away from the first and second brake padswhen the cable brake is fully assembled, the first surface of the collardeclining from either side of the collar toward a centerline of thefirst surface of the collar such that the centerline of the firstsurface of the collar is depressed relative to either side of the firstsurface of the collar with the first surface of the collar slopingforward on either side of the centerline, the collar having an elongatedslot extending on either side of the centerline; providing a pair ofbolts each having a head and a shaft that is threaded at least in part;and providing a pair of wedges each having a hole that is sized toprovide clearance for the shaft of a respective one of the pair of boltsand the slot being sized to provide clearance for the shaft of each ofthe pair of bolts and the cable such that the shaft of each of the pairof bolts can pass through the hole of a respective one of the pair ofwedges and the slot to engage a respective one of the threaded hole ofthe first brake pad and the threaded hole of the second brake pad;positioning each of the pair of wedges in contact with a respectivesloping portion of the first surface of the collar on either side of thecenterline of the first surface of the collar; positioning each of thepair of bolts such that its shaft passes through the hole of therespective one of the pair of wedges and the slot and engages arespective one of the threaded hole of the first brake pad and thethreaded hole of the second brake pad; and tightening the pair of boltswith the head of each of the bolts being in contact with the respectiveone of the pair of wedges to force the first and second brake padstoward one another such that frictional forces between the cable and thefirst and second brake pads are set at a predetermined level.
 59. Themethod according to claim 58, wherein the cable has a longitudinal axis,wherein each of the pair of wedges has a thick side and a thin side,wherein said step of positioning each of the pair of wedges in contactwith a respective sloping portion of the first surface of the collarcomprises positioning the pair of wedges on opposite sides of thecenterline of the first surface of the collar with the cable passingbetween the pair of wedges, and such that each of the pair of wedges isplaced in contact with the respective sloping portion of the firstsurface of the collar with its thick side being positioned closer to thecenterline of the first surface of the collar than its thin side, andsuch that in operation the head of each of the pair of bolts is incontact with a front surface of a respective one of the pair of wedgesthat is essentially perpendicular to the longitudinal axis of the cable.60. The method according to claim 59, further comprising the step ofproviding the slot with a widened middle portion through which the cablepasses and with the widened middle portion having an outline thatfollows a circular arc on either side of the slot.